docs: def importElementTree(module_names=None):
      """Find a working ElementTree implementation, trying the standard
      places that such a thing might show up.
  
      >>> ElementTree = importElementTree()
  
      @param module_names: The names of modules to try to use as
          ElementTree. Defaults to C{L{elementtree_modules}}
  
      @returns: An ElementTree module
      """
      if module_names is None:
          module_names = elementtree_modules
  
      for mod_name in module_names:
          try:
              ElementTree = __import__(mod_name, None, None, ['unused'])
          except ImportError:
              pass
          else:
              # Make sure it can actually parse XML
              try:
                  ElementTree.XML('<unused/>')
              except (SystemExit, MemoryError, AssertionError):
                  raise
              except:
                  logging.exception('Not using ElementTree library %r because it failed to '
                      'parse a trivial document: %s' % mod_name)
              else:
                  return ElementTree
      else:
          raise ImportError('No ElementTree library found. '
                            'You may need to install one. '
                            'Tried importing %r' % (module_names,)
                            )